Atherectomy devices and methods

ABSTRACT

This document describes rotational atherectomy devices and systems for removing or reducing stenotic lesions in blood vessels by rotating an abrasive element within the vessel to partially or completely remove the stenotic lesion material.

CLAIM OF PRIORITY

This application is a divisional application and claims priority to U.S.patent application Ser. No. 14/155,549, filed on Jan. 15, 2014, theentire contents of which are hereby incorporated by reference.

TECHNICAL FIELD

This document relates to rotational atherectomy devices and systems forremoving or reducing stenotic lesions in blood vessels, for example, byrotating an abrasive element within the vessel to partially orcompletely remove the stenotic lesion material.

BACKGROUND

Atherosclerosis, the clogging of arteries with plaque, is often a causeof coronary heart disease or vascular problems in other regions of thebody. Plaque is made up of fat, cholesterol, calcium, and othersubstances found in the blood. Over time, the plaque hardens and narrowsthe arteries. This limits the flow of oxygen-rich blood to organs andother parts of the body.

Blood flow through the peripheral arteries (e.g., carotid, iliac,femoral, renal etc.), can be similarly affected by the development ofatherosclerotic blockages. Peripheral artery disease (PAD) can beserious because without adequate blood flow, the kidneys, legs, arms,and feet may suffer irreversible damage. Left untreated, the tissue candie or harbor infection.

One method of removing or reducing such blockages in blood vessels isknown as rotational atherectomy. In some implementations, a drive shaftcarrying an abrasive burr or other abrasive surface (e.g., formed fromdiamond grit or diamond particles) rotates at a high speed within thevessel, and the clinician operator slowly advances the atherectomydevice distally so that the abrasive burr scrapes against the occludinglesion and disintegrates it, reducing the occlusion and improving theblood flow through the vessel. Examples of some rotational atherectomydevices are depicted in U.S. Patent Publication Nos. 2009/0018564,2009/0182359, 2009/0069829, 2009/0312777, 2009/0326568, 2009/0318942,2010/0010522, 2010/0049226, 2011/0009888, 2012/0109170, and2012/0035633; British Patent Publication No. GB2454943; and U.S. Pat.Nos. 4,990,134; 5,314,438; 6,132,444 and 6,146,395.

SUMMARY

Some embodiments of rotational atherectomy devices and systems describedherein can remove or reduce stenotic lesions in blood vessels byrotating an abrasive element according to a stable and predictableorbiting profile. In particular embodiments, a rotational atherectomydevice comprises an elongate flexible drive shaft with an eccentricabrasive element that is attached to the drive shaft, and two or moreweighted stability elements are attached to the drive shaft such that atleast one stability element is on each side of the abrasive element.Optionally, the stability elements have a center of mass that is axiallyaligned with a central longitudinal axis of the drive shaft while theeccentric abrasive element has a center of mass that is axially offsetfrom central longitudinal axis of the drive shaft. A flexible polymercoating may surround at least a portion of the drive shaft, includingthe stability elements in some embodiments. Also, in some optionalembodiments, a distal extension portion of the drive shaft may extenddistally beyond the distal-most stability element.

In one aspect, this document provides a rotational atherectomy devicefor removing stenotic lesion material from a blood vessel of a patient.In some embodiments, the rotational atherectomy device includes anelongate flexible drive shaft comprising a torque-transmitting coil thatdefines a longitudinal axis, and the drive shaft is configured to rotateabout the longitudinal axis. The rotational atherectomy device may alsoinclude an abrasive element that is attached to the drive shaft suchthat a center of mass of the abrasive element is offset from thelongitudinal axis of the drive shaft. The rotational atherectomy devicemay also include a proximal stability element that is fixed to the driveshaft and that has a center of mass aligned with the longitudinal axisof the drive shaft. The proximal stability element can be proximallyspaced apart from the abrasive element. The rotational atherectomydevice may also include a distal stability element that is fixed to thedrive shaft and that has a center of mass aligned with the longitudinalaxis of the drive shaft. The distal stability element can be distallyspaced apart from the abrasive element. The rotational atherectomydevice may also include a flexible polymer coating along the driveshaft, such that the coating surrounds an outer diameter of at least aportion of drive shaft.

In various implementations of the rotational atherectomy device, theproximal and distal stability elements may be equally spaced apart fromthe abrasive element by a stability spacing distance. The drive shaftmay optionally comprise a distal-most extension portion that extendsdistally of the distal stability element for a distal extensiondistance. The distal extension distance may be substantially greaterthan the stability spacing distance. In some embodiments, the driveshaft may have a central lumen extending along the longitudinal axisthat is configured to receive a guidewire. The proximal and distalstability elements may comprise hollow cylinders that surround thetorque-transmitting coil of the drive shaft. In particular embodiments,the hollow cylinders may have an exterior cylindrical surface that issmoother and different from an abrasive exterior surface of the abrasiveelement. Optionally, the hollow cylinders may have an axial length thatis greater than a maximum exterior diameter of the hollow cylinders. theflexible polymer coating surrounds the torque-transmitting coil of thedrive shaft extending between the first and second stability elements,and exteriors of the abrasive element and the proximal and distalstability elements are uncoated and outwardly exposed.

In some embodiments of the rotational atherectomy device, the flexiblepolymer coating may surround the torque-transmitting coil of the driveshaft extending between the first and second stability elements. In somesuch embodiments, the exteriors of the abrasive element and the proximaland distal stability elements may be uncoated and outwardly exposed. Inparticular embodiments, the flexible polymer coating may surround theouter diameter of the drive shaft extending between the first and secondstability elements and may surround exterior surfaces of the first andsecond stability elements. In some such embodiments, an abrasive outersurface of the abrasive element may be uncoated and outwardly exposed.Optionally, the flexible polymer coating may comprise afluid-impermeable material that provides a fluid-impermeable lumen alongthe drive shaft. In some embodiments, the flexible polymer coating mayhave a different durometer at different locations on the drive shaft.

In some implementations, the rotational atherectomy device may furthercomprise a second proximal stability element and a second distalstability element. Optionally, the second proximal stability element maybe located proximally to the abrasive element and the second distalstability element may be located distally to the abrasive element. Insome embodiments, the abrasive element may comprise two or more abrasivesegments that may be positioned adjacent to one another along the driveshaft. In particular embodiments, the abrasive element may comprise atleast three segments, and a middle segment may optionally have a largerouter diameter than a proximal segment and a larger outer diameter thana distal segment.

In another aspect, this document provides a system for performingrotational atherectomy to remove stenotic lesion material from a bloodvessel of a patient. In some embodiments, the system includes anelongate flush tube defining a first lumen and a second lumen. The flushtube may include an inflatable balloon member attached to andsurrounding an outer diameter of a distal end portion of the flush tube.The balloon member can be in fluid communication with the first lumen.The balloon member can be configured to contact a blood vessel wall whenthe balloon member is in an inflated configuration. The system alsoincludes a rotational atherectomy device. The rotational atherectomydevice can include an elongate flexible drive shaft defining alongitudinal axis. The drive shaft can be configured for rotation aboutthe longitudinal axis and configured to be at least partially disposedwithin the second lumen when the system is used for performing therotational atherectomy. The rotational atherectomy device can alsoinclude an abrasive element that is fixed to the drive shaft such that acenter of mass of the abrasive element is offset from the longitudinalaxis. The rotational atherectomy device can also include a stabilityelement that is fixed to the drive shaft and that has a center of massaligned with the longitudinal axis, the second stability element beingdistally spaced apart from the abrasive element.

In various implementations of the system for performing rotationalatherectomy, the balloon member may optionally define channel spacesthat are configured to allow blood flow therethrough when the balloonmember is in the inflated configuration within the blood vessel. In someembodiments, the system for performing rotational atherectomy canfurther comprise a second stability element that may be fixed to thedrive shaft and located proximally of the abrasive element. The systemmay further comprise a guidewire that can be configured to slidablywithdrawn into a fluid-impermeable lumen of the drive shaft ofrotational atherectomy device. In some embodiments of the system forperforming rotational atherectomy, the rotational atherectomy device mayfurther comprise a flexible polymer coating along the drive shaft suchthat the coating may surround an outer diameter of at least a portion ofdrive shaft.

In another aspect, this document provides a method for performingrotational atherectomy to remove stenotic lesion material from a bloodvessel of a patient. In some embodiments, the method includes deliveringa rotational atherectomy device into the blood vessel. In someembodiments, the rotational atherectomy device includes an elongateflexible drive shaft defining a longitudinal axis. The drive shaft canbe configured for rotation about the longitudinal axis. The rotationalatherectomy device can also include an abrasive element that is fixed tothe drive shaft such that a center of mass of the abrasive element isoffset from the longitudinal axis. The rotational atherectomy device canalso include a first stability element that is fixed to the drive shaftand that has a center of mass aligned with the longitudinal axis. Thefirst stability element can be proximally spaced apart from the abrasiveelement. The rotational atherectomy device can also include a secondstability element that is fixed to the drive shaft and that has a centerof mass aligned with the longitudinal axis. The second stability elementcan be distally spaced apart from the abrasive element. The method forperforming rotational atherectomy to remove stenotic lesion materialfrom a blood vessel of a patient can also include rotating the driveshaft about the longitudinal axis such that a portion of the drive shaftextending between the first and second stability elements traces agenerally bicone shape.

In various implementations of the method for performing rotationalatherectomy to remove stenotic lesion material from a blood vessel of apatient, during the rotation, the abrasive element may have an orbitalpath about an axis of rotation. The orbital path may have asubstantially greater diameter than a travel path of each of the firstand second stability elements. In some embodiments, the method forperforming rotational atherectomy may further comprise translating thedrive shaft distally during the rotating the drive shaft. The rotatingthe drive shaft may cause the abrasive element to remove the stenoticlesion material from a vessel wall. In some embodiments, the method forperforming rotational atherectomy may further comprise delivering anelongate flush tube into the blood vessel. The flush tube may define afirst lumen and a second lumen. The flush tube may include a balloonmember attached to and surrounding an outer diameter of a distal endportion of the flush tube. The balloon member may be in fluidcommunication with the first lumen, and at least a portion of the driveshaft may be disposed within the second lumen. Optionally, the methodfor performing rotational atherectomy may further comprise inflating theballoon member by supplying an inflation fluid through the first lumen.The inflating may cause the balloon member to expand into contact withthe blood vessel.

Some of the embodiments described herein may provide one or more of thefollowing advantages. First, some embodiments of the rotationalatherectomy devices and systems operate with a stable and predictablerotary motion profile for enhanced atherectomy performance. That is,when the device is being rotated in operation, the eccentric abrasiveelement follows a predefined, consistent orbital path (offset from anaxis of rotation of the device) while the stability elements and otherportions of the device remain on or near to the axis of rotation for thedrive shaft in a stable manner. This predictable orbital motion profilecan be attained by the use of design features including, but not limitedto, stability elements that have centers of mass that are coaxial withthe longitudinal axis of the drive shaft, a polymeric coating on atleast a portion of the drive shaft, a distal-most drive shaft extensionportion, and the like. Some embodiments of the rotational atherectomydevices and systems provided herein may include one or more of suchdesign features.

Second, some embodiments of the rotational atherectomy devices andsystems provided herein can be used to treat large-diameter vessels(including renal and iliac arteries having an internal diameter that ismultiple time greater than the outer diameter of the abrasive element)while requiring only a small introducer sheath size. In other words, insome embodiments the rotating eccentric abrasive element traces anorbital path that is substantially larger than the outer diameter of therotational atherectomy device in the non-rotating state. This featureimproves the ability of the rotational atherectomy devices providedherein to treat very large vessels while still fitting within a smallintroducer size. In some embodiments, this feature can be at leastpartially attained when a guidewire that is used to navigate theatherectomy device to the site of the target lesion is withdrawn priorto rotation of the drive shaft, such that the guidewire does not resistthe deflection of the drive shaft during rotation. Further, in someembodiments this feature can be at least partially attained by using aneccentric abrasive element that has a high eccentric mass (e.g., thecenter of mass of the abrasive element is significantly offset from thecentral longitudinal axis of the drive shaft).

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the invention will be apparent from thedescription and drawings, and from the claims.

DESCRIPTION OF DRAWINGS

FIG. 1A is a side view of a distal portion of a rotational atherectomydevice, in accordance with some embodiments.

FIG. 1B is a longitudinal cross-sectional view of a portion of therotational atherectomy device of FIG. 1A, including the device'seccentric abrasive element.

FIGS. 1C and 1D are longitudinal cross-sectional views of portions ofthe rotational atherectomy device of FIG. 1A that include the device'sstability elements.

FIG. 2A is a side view of the rotational atherectomy device of FIG. 1Aafter being deployed within a vessel that is shown in longitudinalcross-section.

FIGS. 2B through 2D illustrate the rotational atherectomy device of FIG.2A being rotated to provide an atherectomy treatment.

FIG. 3A is a side view of a distal portion of another rotationalatherectomy device, in accordance with some embodiments.

FIG. 3B is a longitudinal cross-sectional view of a portion of therotational atherectomy device of FIG. 3A, including the device'seccentric abrasive element.

FIGS. 3C and 3D are longitudinal cross-sectional views of portions ofthe rotational atherectomy device of FIG. 3A that include the device'sstability elements.

FIG. 4A is a side view of a distal portion of another rotationalatherectomy device, in accordance with some embodiments.

FIG. 4B is a longitudinal cross-sectional view of a portion of therotational atherectomy device of FIG. 4A, including some of the device'sstability elements.

FIG. 5A is a side view of a distal portion of another rotationalatherectomy device, in accordance with some embodiments.

FIG. 5B is a longitudinal cross-sectional view of a portion of therotational atherectomy device of FIG. 5A, including some of the device'sstability elements.

FIG. 6 is a side view of a distal portion of another rotationalatherectomy device, in accordance with some embodiments.

FIG. 6A is a side view of a distal portion of yet another rotationalatherectomy device, in accordance with some embodiments.

FIG. 7 is a side view of a distal portion of a rotational atherectomysystem, including a flush tube with a proximal stabilization balloon, inaccordance with some embodiments.

FIG. 8 is a side view of the rotational atherectomy system of FIG. 7deployed within a vessel that is shown in longitudinal cross-section.

FIG. 9 is a side view of another rotational atherectomy system, inaccordance with some embodiments, deployed within a vessel that is shownin longitudinal cross-section.

Like reference symbols in the various drawings indicate like elements.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

Referring to FIG. 1A, in some embodiments a rotational atherectomydevice 100 can include a drive shaft 110, a proximal stability element120, a distal stability element 130, and an eccentric abrasive element140. In this embodiment, the stability elements 120 and 130 have acenter of mass that is axially aligned with a central longitudinal axis102 of the drive shaft 110 while the eccentric abrasive element 140 hasa center of mass that is axially offset from central longitudinal axis102 of the drive shaft 110. As will be described further below, therotational atherectomy device 100 is configured to remove some or all ofa stenotic lesion from within a vessel of a patient. As the rotationalatherectomy device 100 is rotated about its longitudinal axis 102,centrifugal force will cause the eccentric abrasive element 140 tofollow a transverse circular orbit around the longitudinal axis. Theorbiting eccentric abrasive element 140 will contact the stenotic lesionto ablate the lesion to a reduced size.

The proximal stability element 120 and the distal stability element 130are each fixedly attached to the drive shaft 110. The proximal stabilityelement 120 is located proximal to the distal stability element 130. Theeccentric abrasive element 140 is located between the proximal stabilityelement 120 and the distal stability element 130. The eccentric abrasiveelement 140 is also fixedly attached to the drive shaft 110. A distaldrive shaft extension portion 112 of the drive shaft 110 extendsdistally of the distal stability element 130.

Referring now to FIGS. 1A-1D, the elongate drive shaft 110 of rotationalatherectomy device 100 is laterally flexible so that the drive shaft 110can readily conform to the tortuous non-linear vasculature of thepatient, and so that a portion of the drive shaft 110 adjacent to theeccentric abrasive element 140 will laterally deflect when acted on bythe centrifugal forces resulting from the rotation of the eccentricabrasive element 120. In this embodiment, the drive shaft 110 comprisesone or more helically wound wires 114 (or filars 114). In someembodiments, the one or more helically wound wires 114 are made of ametallic material such as, but not limited to, stainless steel (e.g.,316, 316L, or 316LVM), nitinol, titanium, titanium alloys (e.g.,titanium beta 3), carbon steel, or another suitable metal or metalalloy. In some alternative embodiments, the filars 114 are or includegraphite, Kevlar, or a polymeric material. In some embodiments, thefilars 114 can be woven, rather than wound. In some embodiments,individual filars 114 can comprise multiple strands of material that aretwisted, woven, or otherwise coupled together to form a filar 114. Insome embodiments, the filars 114 have different cross-sectionalgeometries (size or shape) at different portions along the axial lengthof the drive shaft 110. In some embodiments, the filars 114 have across-sectional geometry other than a circle, e.g., an ovular, square,triangular, or another suitable shape. The one or more helically woundwires 114 can transmit a torque from a rotary actuator (comprising, forexample, a pneumatic motor or an electric motor) located exterior to thepatient (not shown in FIG. 1A). The torque from the external actuator istransmitted via the drive shaft 110 to the elements 120, 130, 140, and112 along the distal portion of the rotational atherectomy device 100.

In this embodiment, the drive shaft 110 has a hollow core. That is, thedrive shaft 110 has a longitudinal lumen 115 running therethrough. Thelumen 115 can be used to receive a guidewire therein, as will bedescribed further below. In some embodiments, the lumen can be used toaspirate particulate or to convey fluids that are beneficial for theatherectomy procedure.

The size of the drive shaft 110 can be scaled commensurately with thesize of vessels to be treated and the performance desired. In a firstexample embodiment, the outer diameter of the drive shaft 110 is about0.030 inches (0.76 mm) and the inner diameter is about 0.020 inches(0.51 mm). The first example embodiment uses a six (6) filarconfiguration with each filar having a diameter of about 0.005 inches(0.13 mm). In a second example embodiment, the outer diameter of thedrive shaft 110 is about 0.051 inches (1.30 mm) and the inner diameteris about 0.041 inches (1.04 mm). The second example embodiment uses anine (9) filar configuration with each filar having a diameter of about0.005 inches (0.13 mm).

From the description provided herein, it should be understood that arange of sizes of drive shafts 110 are contemplated. For example, theouter diameter of the drive shaft 110 may range from about 0.020 inchesto about 0.100 inches (0.50 mm to 2.54 mm). The drive shafts 110 canhave any number of filars, and the diameter of the filars may range fromabout 0.002 inches to about 0.020 inches (0.05 mm to 0.51 mm).

In the depicted embodiment, the drive shaft 110 also includes a coating116 on the outer diameter of the drive shaft 110. The coating 116 mayalso be described as a jacket, a sleeve, a covering, a casing, and thelike. In some embodiments, the coating 116 adds column strength to thedrive shaft 110 to facilitate a greater ability to push the drive shaft110 through stenotic lesions. In addition, the coating 116 can enhancethe stability of the drive shaft 110 during use. In some embodiments,the coating 116 is a flexible polymer coating that surrounds an outerdiameter of at least a portion of drive shaft 110 (e.g., the portion ofthe drive shaft located exterior to the patient and extending fully toat least the proximal stability element 120). In particular embodiments,the coating 116 is a fluid impermeable material such that the lumen 115provides a fluid impermeable flow path to the distal portion of thedevice 100.

The coating 116 may be made of materials including, but not limited to,PEBEX, PICOFLEX, TECOFLEX, PTFE, ePTFE, FEP, PEEK, silicone, PVC,urethane, polyethylene, polypropylene, and the like, and combinationsthereof. In some embodiments, a second coating that is analogous to thecoating 116 may also be included on the inner diameter of the driveshaft 110. Alternatively, the coating on the inner diameter of the driveshaft 110 may be included as an alternative to the coating 116 on theouter diameter of the drive shaft 110. In the depicted embodiment, thecoating 116 covers not only the drive shaft 110, but also the proximalstability element 120, the distal stability element 130, and the distalextension portion 112, thereby leaving only the abrasive element 140exposed (non-coated) along the distal portion of the device 100. Inalternative embodiments, the proximal stability element 120 and thedistal stability element 130 are not covered with the coating 116, andthus would be exposed like the abrasive element 140. In someembodiments, two or more layers of the coating 116 can be included onportions of the drive shaft 110. Further, in some embodiments differentcoating materials (e.g., with different durometers and/or stiffnesses)can be used at different locations on the drive shaft 110. For example,a first portion of the coating 116 extending along the drive shaft thatis proximal to the proximal stability element 120 and distal to thedistal stability element 130 can have a first durometer that isdifferent from (e.g., substantially higher than) a second durometer of asecond portion of the coating 116 extending between the proximalstability element 120 and the distal stability element 130.

Still referring to FIGS. 1A-1D, in this embodiment, the proximalstability element 120 and the distal stability element 130 are eachhollow cylindrical members having an inner diameter that surrounds aportion of the outer diameter of the drive shaft 110. In someembodiments, the proximal stability element 120 and the distal stabilityelement 130 have an axial length that is greater than a maximum exteriordiameter of the proximal stability element 120 and the distal stabilityelement 130. As shown in FIGS. 1C-1D, the proximal stability element 120and the distal stability element 130 are coaxial with the longitudinalaxis 102 of the drive shaft 110. Therefore, the centers of mass of theproximal stability element 120 and the distal stability element 130 areaxially aligned (non-eccentric) with the longitudinal axis 102. Inalternative rotational atherectomy device embodiments, stabilityelements that have centers of mass that are eccentric in relation to thelongitudinal axis 102 may be included in addition to, or as analternative to, the coaxial proximal and distal stability elements 120and 130. For example, in some alternative embodiments, the stabilityelements can have centers of mass that are eccentric in relation to thelongitudinal axis 102 and that are offset 180 degrees in relation to thecenter of mass of the eccentric abrasive element 140.

The proximal stability element 120 and the distal stability element 130may be made of a suitable biocompatible material, such as ahigher-density biocompatible material. For example, in some embodimentsthe proximal stability element 120 and the distal stability element 130may be made of metallic materials such as stainless steel, tungsten,molybdenum, iridium, cobalt, cadmium, and the like, and alloys thereof.The proximal stability element 120 and the distal stability element 130may be mounted to the filars 114 using a biocompatible adhesive, bywelding, by press fitting, and the like, and by combinations thereof.The coating 116 may also be used to attach or to supplement theattachment of the proximal stability element 120 and the distalstability element 130 to the filars 114 of the drive shaft 110.Alternatively, the proximal stability element 120 and the distalstability element 130 can be integrally formed as a unitary structurewith the filars 114 of the drive shaft 110 (e.g., using filars of adifferent size or density, using filars that are double-wound to providemultiple filar layers, or the like). The proximal stability element 120and the distal stability element 130 have an exterior cylindricalsurface that is smoother and different from an abrasive exterior surfaceof the abrasive element 140.

Still referring to FIGS. 1A-1D, the eccentric abrasive element 140,which may also be referred to as a burr, can comprise a biocompatiblematerial that is coated with an abrasive media such as diamond grit,diamond particles, silicon carbide, and the like. As shown in FIG. 1B,the center of mass of the eccentric abrasive element 140 is offset fromthe longitudinal axis 102 of the rotational atherectomy device 100. Theeccentric abrasive element 140 has at least one outwardly exposedsurface (the abrasive surface 142) that is not covered by the coating116. Therefore, as the eccentric abrasive element 140 is rotated in anorbital path, at least a portion of the abrasive surface 142 of theeccentric abrasive element 140 can make contact with surroundingstenotic lesion material. As with the stability elements 120 and 130,the eccentric abrasive element 140 may be mounted to the filars 114using a biocompatible adhesive, welding, press fitting, and the like.Alternatively, the eccentric abrasive element 140 can be integrallyformed as a unitary structure with the filars 114 of the drive shaft 110(e.g., using filars that are wound in a different pattern to create anaxially offset structure, or the like).

Referring again to FIG. 1A, in some embodiments, the spacing of theproximal stability element 120 and the distal stability element 130(relative to the eccentric abrasive element 140) and the length of thedistal extension portion 112 can be selected to advantageously provide astable and predictable rotary motion profile during high-speed rotationof the device 100. For example, in this embodiment, the eccentricabrasive element 140 is separated from the proximal stability element120 by a distance D1. The eccentric abrasive element 140 is separatedfrom the distal stability element 130 by a distance D2. In the depictedembodiment, the distances D1 and D2 are equal. The distal driveshaftextension portion 112 is a portion of the driveshaft 110 that extendsdistally from the distal stability element 130 by a distance D3. In use,the distal driveshaft extension portion 112 adds to the stability of therotational atherectomy device 100, while the eccentric abrasive element140 is following its orbital path around the longitudinal axis 102. Inthe depicted embodiment, the distal driveshaft extension portion 112 iscovered with the coating 116. In this particular embodiment, thedistance D3 is significantly greater than the distance D1 or D2.

In embodiments that include the distal driveshaft extension portion 112,the ratio of the distance D3 to the distance D1 (or D2) can be selectedto affect the performance characteristics (e.g., the stability of therotary motion profile) of the rotational atherectomy device 100. In someembodiments, the ratio of D3:D1 (or D3:D2) is about 1:1, about 1.5:1,about 2:1, about 2.5:1, about 3:1, or higher than 3:1 It should beunderstood from the description herein, that in some alternativeembodiments, the distances D1 and D2 may be unequal.

Referring now to FIG. 2A, the rotational atherectomy device 100 can beused to treat a vessel 180 having a stenotic lesion 190 along an innerwall 182 of the vessel 180. The rotational atherectomy device 100 isused to fully or partially remove the stenotic lesion 190, therebyremoving or reducing the blockage within the vessel 180 caused by thestenotic lesion 190. By performing such a treatment, the blood flowthrough the vessel 180 may be thereafter increased or otherwiseimproved. The vessel 180 and lesion 190 are shown in longitudinalcross-sectional views to enable visualization of the rotationalatherectomy device 100.

Briefly, in some implementations the following activities may occur toprovide the deployed arrangement shown in FIG. 2A. An introducer sheath(not shown in FIG. 2A) can be percutaneously advanced into thevasculature of the patient and navigated within the patient'svasculature to the targeted vessel 180. Techniques such as x-rayfluoroscopy or ultrasonic imaging may be used to provide visualizationof the introducer sheath and other atherectomy system components duringplacement. A guidewire (not shown in FIG. 2A) can then be insertedthrough a lumen of the introducer sheath and advanced to extend beyondthe distal tip of the introducer sheath (and, optionally, through thearea of the stenotic lesion 190). Next, the rotational atherectomydevice 100 can be inserted over the guidewire (via the lumen 115) andadvanced to the deployed position shown (optionally, the introducedsheath can be withdrawn before the rotational atherectomy device isadvanced over the guidewire). In some implementations, a flush tube(e.g., refer to FIGS. 8 and 9) may surround a portion of the drive shaft110 while the rotational atherectomy device 100 is so inserted over theguidewire.

In the deployed position as shown in the embodiment depicted in FIG. 2A,the eccentric abrasive element 140 is positioned near to the lesion 190such that the eccentric abrasive element 140 can contact the lesion 190when the drive shaft 110 is later rotated and advanced to remove thelesion 190. After the rotational atherectomy device 100 is placed in thedeployed position, the guidewire is pulled back from within the lumen115 of the drive shaft 110. In some implementations, the guidewire iswithdrawn completely out of the lumen 115 of the drive shaft 110. Inother implementations, the guidewire is withdrawn only partially (e.g.,to a position that is proximal of the proximal stability element 120 andpreferably proximal of the distal tip of the flush tube. That is, insome implementations a portion of the guidewire remains within the lumenof the drive shaft 110 during rotation of the drive shaft 110, butremains only in the portion that is not subject to the significantorbital path in the area of the abrasive element 140. After theguidewire is withdraw (fully or partially), the drive shaft 110 is thenrotated (via the actuator located at the proximal end outside of thepatient's body) at a high degree of rotation (e.g., 20,000-160,000 rpm)such that the eccentric abrasive element 140 revolves in an orbital pathabout an axis of rotation 103 and thereby contacts and removes portionsof the lesion 190, even those portions of the lesion 190 that are spacedfurther from the axis of rotation 103 than the maximum diameter of theabrasive element 140.

Referring now to FIGS. 2B through 2D, the rotational atherectomy device100 is depicted during the high-speed rotation of the drive shaft 110.The centrifugal force acting on the eccentrically weighted abrasiveelement 140 causes the eccentric abrasive element 140 to orbit in anorbital path around the axis of rotation 103. In some implementations,the orbital path can be somewhat similar to the motion of a “jump rope.”As shown in FIGS. 2B-2D, some portions of the drive shaft 102 (e.g., aportion that is proximal of the proximal stability element 120 andanother portion that is distal of the distal stability element 130) canbe aligned with the axis of rotation 103, but the particular portion ofthe drive shaft 110 adjacent to the abrasive element 140 is not alignedwith the axis of rotation 103 (and instead orbits around the axis 103).In such circumstances, the longitudinal axis 102 of the drive shaft 110in those particular portions (e.g., the shaft portion that is proximalof the proximal stability element 120 and the other shaft portion thatis distal of the distal stability element 130) may be generally axiallyaligned with the axis of rotation 103, as shown in FIGS. 2B-D. It shouldbe understood from the description herein that the term “generallyaxially aligned” is intended to account for the momentary variances thatoccur in the drive shaft position due to the high-speed rotation of thedrive shaft, but that the longitudinal axis 102′ (FIGS. 2B-2C) at theparticular portion of the drive shaft 110 adjacent to the abrasiveelement 140 is not generally axially aligned with the axis of rotation103 during the high speed rotation. In some implementations, as theeccentric abrasive element 140 rotates, the clinician operator slowlyadvances the atherectomy device 100 distally (an, optionally,reciprocates both distally and proximally) in the axial direction sothat the abrasive surface of the eccentric abrasive element 140 scrapesagainst additional portions of the occluding lesion 190 to reduce thesize of the occlusion, and to thereby improve the blood flow through thevessel 180.

During rotation of the atherectomy device 100, the proximal and distalstability elements 120 and 130, as well as the distal drive shaftextension portion 112, can be configured to advantageously achieveimproved stability for the drive shaft 110 relative to the axis orrotation 103. For example, the device 100 can achieve a stable andpredictable rotary motion profile in which the shaft portion that isproximal of the proximal stability element 120 and the other shaftportion that is distal of the distal stability element 130 remaingenerally aligned with the axis of rotation 103, even though theparticular portion of the drive shaft 110 adjacent to the abrasiveelement 140 is not generally aligned with the axis of rotation 103 (andinstead orbits around the axis 103). In this stability rotary motionprofile, the eccentric abrasive element can follow a predictable orbitalpath (offset from an axis of rotation 103), yet other portions of thedrive shaft 110 (especially the distal extension 112) can remain in asubstantially stable axial alignment that greatly reduces the likelihoodof uncontrolled whipping of the distal-most tip of the drive shaft 110(which might cause unnecessary damage to the vessel wall 182). Forexample, such stability can be achieved by selecting some or all of thefollowing design aspects of the rotational atherectomy device 100: (i)the mass of the proximal and distal stability elements 120 and 130, (ii)the length of the distal drive shaft extension portion 112 as a ratio tothe distance between the proximal and distal stability elements 120 and130 and the eccentric abrasive element 140, and (iii) the stiffness ofthe drive shaft 110 including any coating 116 on the drive shaft 110. Insome embodiments, different coatings 116 (e.g., different materialsand/or durometers) are used on different portions of the drive shaft 110to enhance the in-operation stability of the rotational atherectomydevice 100. In particular embodiments, multiple layers of coatings canbe used on different portions of the drive shaft 110 to enhance thein-operation stability of the rotational atherectomy device 100.

As best seen in FIG. 2D, when rotating, the operative portion of thedrive shaft 110 between the proximal and distal support elements 120 and130 traces a generally bicone shape. By providing this predicable shapeduring high-speed rotation of the drive shaft 110, the shaft portionthat is proximal of the proximal stability element 120 and the othershaft portion that is distal of the distal stability element 130 canremain both generally aligned with one another and can remain in agenerally stable position within the vessel 180 (e.g., centrally alignedwith the vessel 180). Also, when the device 100 provides this stable andpredictable rotary motion profile, the orbital path of the abrasiveelement 140 is substantially greater than any orbital path of theproximal and distal stability elements 120 and 130 (if those elements120 and 130 have any orbital path at all). As shown in the example inFIG. 2D, the orbital path diameter of the abrasive element 140 issubstantially greater than the maximum diameter of the rotational pathof each of the proximal and distal stability elements 120 and 130.

Referring now to FIGS. 3A through 3D, some embodiments of a rotationalatherectomy device 300 can include proximal and distal stabilityelements 320 and 330 that are uncoated in this embodiment. The otheraspects (e.g., materials, structure, construction, and alternatives) ofthe rotational atherectomy device 300 are similar to the rotationalatherectomy device 100 described above.

In the depicted embodiment, a coating 316 surrounds at least somesections of filars 314 of drive shaft 310 (e.g., from the stabilityelements 320 and 330 to an eccentric abrasive element 340, and on adistal driveshaft extension portion 312). However, the coating 316 doesnot surround the outer diameters of the proximal and distal stabilityelements 320 and 330 in this embodiment. In some embodiments, onestability element 320 or 330 may be coated while the other stabilityelement 320 or 330 remains uncoated.

Referring now to FIGS. 4A and 4B, some embodiments of a rotationalatherectomy device 400 can include multiple proximal stability elements420 a-b and multiple distal stability elements 430 a-b. For example, asshown in FIGS. 4A-4B, the atherectomy device 400 includes two proximalstability elements 420 a-b and two distal stability elements 430 a-b.The other aspects (e.g., materials, structure, construction, andalternatives) of the rotational atherectomy device 400 can be similar tothe rotational atherectomy device 100 described above. In someembodiments, the inclusion of such multiple stability elements canenhance the stability and predictability of rotary motion profile of theabrasive element 440 and the drive shaft 410 along the distal portion ofthe rotational atherectomy device 400.

In the depicted embodiment, each of the stability elements 420 a-b and430 a-b has a center of mass that is axially aligned with a longitudinalaxis 402 of drive shaft 410. However, in alternative embodiments thecenter of mass of one or more of the stability elements 420 a-b and/or430 a-b may be offset from the longitudinal axis 402. In the depictedembodiment, a distal drive shaft extension portion 412 extends distallyfrom the distal-most stability element 430 b. However, in alternativeembodiments, the distal driveshaft extension portion 412 may be omitted.In the depicted embodiment, the outer diameters of the stabilityelements 420 a-b and 430 a-b are surrounded by a coating 416, which canbe similar to the coating 116 described in connection with FIGS. 1A-D.However, in alternative embodiments one or more of the stabilityelements 420 a-b and 430 a-b may be uncoated.

In some embodiments, the stability elements 420 a and 420 b (and thesame applies to the stability elements 430 a and 430 b) are spacedclosely enough together such that the stability elements 420 a and 420 bperform much like a single stability element to stabilize the driveshaft 410. In alternative embodiments, the stability elements 420 a and420 b (and the same applies to the stability elements 430 a and 430 b)are spaced apart from each other enough such that the stability elements420 a and 420 b perform much like independent stability elements tostabilize the drive shaft 410.

Referring now to FIGS. 5A and 5B, some embodiments of a rotationalatherectomy device 500 can include three proximal stability elements 520a-c and three distal stability elements 530 a-c. The other aspects(e.g., materials, structure, construction, and alternatives) of therotational atherectomy device 500 can be similar to the rotationalatherectomy device 100 described above. In some embodiments, theinclusion of such multiple stability elements can enhance the stabilityand predictability of rotary motion profile of the abrasive element 540and the drive shaft 510 along the distal portion of the rotationalatherectomy device 500.

In the depicted embodiment, each of the stability elements 520 a-c and530 a-c has a center of mass that is axially aligned with a longitudinalaxis 502 of drive shaft 510. However, in alternative embodiments thecenter of mass of one or more of the stability elements 520 a-b-c and530 a-b-c may be offset from the longitudinal axis 502. In the depictedembodiment, a distal driveshaft extension portion 512 extends distallyfrom the distal-most stability element 530 c. However, in alternativeembodiments the distal drive shaft extension portion 512 may be omitted.In the depicted embodiment, the outer diameters of the stabilityelements 520 a-b-c and 530 a-b-c are uncoated. However, in alternativeembodiments the outer diameters of one or more of the stability elements520 a-b-c and 530 a-b-c may be surrounded by a coating 516, which can besimilar to the coating 116 described in connection with FIGS. 1A-D.

Referring now to FIG. 6, some embodiments of a rotational atherectomydevice 600 can include a segmented eccentric abrasive element thatincludes multiple side-by-side abrasive segments 640 a-c. The otheraspects (e.g., materials, structure, construction, and alternatives) ofthe rotational atherectomy device 600 are similar to the rotationalatherectomy device 100 described above. In some embodiments, theinclusion of the segmented abrasive element 640 a-c can enhance theflexibility of the portion of the drive shaft 610 within the segments640 a-c, thereby providing (in some circumstances) a greater orbitalpath diameter as compared to other embodiments having a single, elongateabrasive element. The segmentation of the abrasive element 640 a-c canalso provide for a wider abrasive element, thereby increasing thetreatment efficiency (e.g., reducing the treatment time) of therotational atherectomy device 600.

In the depicted embodiment, the segmented eccentric abrasive element 640a-c includes three segments. In alternative embodiments, two, four,five, or more than five segments can be included (refer, for example, toFIG. 6A depicting five). In the depicted embodiment, all three segments640 a-c have centers of mass that are offset from a longitudinal axis602 of a drive shaft 610. In alternative embodiments, one or more of thesegments may have a center of mass that is aligned with the longitudinalaxis 602 while the other segment(s) is eccentric and thus not alignedwith the longitudinal axis 602. In the depicted embodiment, all threesegments 640 a-c are shaped as ellipsoids. In alternative embodiments,one or more of the segments may have a different shape such as, but notlimited to, spherical (refer, for example, to FIG. 6A), cylindrical,conical, frustro conical, polyhedral, and the like. In the depictedembodiment (FIG. 6), the outer diameters of the two outer abrasiveelements 640 a and 640 c are smaller than the central abrasive element640 b (refer also, for example, to FIG. 6A). Together, the segmentedeccentric abrasive element 640 a-b-c therefore has a tapered outerprofile. In alternative embodiments, all segments may have essentiallythe same outer diameter, or may define a different outer profile shape.

Referring now to FIG. 7, as previously described herein, someembodiments of a rotational atherectomy system include a rotationalatherectomy device 700 and a flush tube 750. The rotational atherectomydevice 700 can be configured as any of the above-described atherectomydevices 100, 300, 400, 500, and 600. In use, a portion of a drive shaft710 of the rotational atherectomy device 700 can be slidably positionedwithin a lumen of the flush tube 750. As such, while the drive shaft 710is rotating at a high speed (e.g., 20,000 to 180,000 rpm), the flushtube 750 can remain stationary relative to the vessel wall. In thesecircumstances, the flush tube 750 can further enhance to the stabilityof the portion of the drive shaft 710 that is proximal to the abrasiveelement (not shown in FIG. 7, refer to FIG. 8) and improve thepredictability of the rotary motion profile of the abrasive element. Insome embodiments, the flush tube also increases the column strength (andtherefore the ability to be pushed) of the drive shaft and flush tubesystem 710 and 750 during the system's advancement over the guidewirewithin the vasculature of the patient.

In this embodiment, the flush tube 750 includes a multi-lumen shaft 752and a stabilization balloon 754, which can be inflated after deploymentinto the targeted vessel. The stabilization balloon 754 is attached to adistal end portion of the multi-lumen shaft 752 and is in fluidcommunication with an inflation lumen of the multi-lumen shaft 752. Theinflation lumen of the multi-lumen shaft 752 can be used to convey aninflation fluid (e.g., saline) to the stabilization balloon 754. Wheninflation fluid is supplied to the stabilization balloon 754, thestabilization balloon 754 can expand to the configuration shown.Conversely, when inflation fluid is not supplied to the stabilizationballoon 754, the stabilization balloon 754 contracts to a configurationthat is smaller in size than the expanded configuration shown.

In addition to the inflation lumen, the multi-lumen shaft 752 includes alongitudinal drive shaft lumen in which a portion of the drive shaft 710can be slidably positioned. A physical clearance exists between theouter diameter of the drive shaft 710 and the inner diameter of thedrive shaft lumen. The clearance allows the drive shaft 710 to freelyrotate while the flush tube 750 is stationary relative to the vessel. Insome embodiments, the clearance is in a range of about 0.05 mm to about0.15 mm, or about 0.13 mm to about 0.23 mm, or about 0.20 mm to about0.30 mm, or about 0.28 mm to about 0.38 mm, or about 0.35 mm to about0.46 mm, or more than about 0.46 mm. In addition to allowing the driveshaft 710 to rotate while the flush tube 750 is stationary, theclearance therebetween can be used to covey a flush fluid (e.g.,saline). The flush fluid prevents blood from the vessel being treatedfrom backing up into the clearance space. In addition, in someembodiments the flush fluid can provide cooling and lubrication to thesurface friction between the drive shaft 710 and the drive shaft lumenof the flush tube 750 as the drive shaft 710 is rotating.

Still referring to FIG. 7, in some embodiments, the stabilizationballoon 754 can include one or more ribs 756. As will be describedfurther below, the ribs 756 facilitate the flow of blood past thestabilization balloon 754 even while the stabilization balloon 754 is inan expanded configuration and in contact with an inner wall of thetargeted vessel. This feature for facilitating blood flow isadvantageous in that blood flow is not cut off during an atherectomyprocedure. While the depicted embodiment of stabilization balloon 754includes the ribs 756, in alternative embodiments other types offeatures for facilitating blood flow through or around a stabilizationballoon can be included. For example, in some embodiments features suchas, but not limited to, through-holes or lumens, grooves, and the like,can be included to facilitate blood flow through or around astabilization balloon.

Referring to FIG. 8, the rotational atherectomy device 700 inconjunction with the flush tube 750 can be used to provide anatherectomy treatment to a stenotic lesion 890 within a vessel 880. Thevessel 880 and lesion 890 are shown in longitudinal cross-sectionalviews to enable visualization of the rotational atherectomy device 700and the flush tube 750. In some implementations, the flush tube 750 canfurther enhance to the stability of the portion of the drive shaft 710that is proximal to the abrasive element 740 and improve thepredictability of the rotary motion profile of the abrasive element 740.

During rotation of the drive shaft 710 about its axis 702, thestabilization balloon 756 is in an expanded configuration as shown. Assuch, the ribs 756 make contact with the inner wall of the vessel 880 tomaintain the position of the balloon 756 relative to the vessel 880while also permitting continued blood flow pass the balloon 756. Thedrive shaft 710 can then be rotated to cause the eccentric abrasiveelement 740 to orbit around the axis of rotation 703 of the atherectomydevice 700 to ablate the lesion 890. Similar to previously describedembodiments, the device 700 can achieve a stable and predictable rotarymotion profile in which the shaft portion that is proximal of theproximal stability element 720 and the other shaft portion that isdistal of the distal stability element 730 remain generally aligned withthe axis of rotation 703, even though the particular portion of thedrive shaft 710 adjacent to the abrasive element 740 is not generallyaligned with the axis of rotation 703 (and instead orbits around theaxis 703). The flush tube 750 remains substantially stationary as thedrive shaft 710 is rotated. The contact between the ribs 756 and theinner wall of the vessel 880 help the stabilization balloon 754 tofurther stabilize the atherectomy device 700 during rotation and to alsocentrally position the shaft portion that is proximal of the proximalstability element 720 within the targeted vessel 880. During theatherectomy procedure, on-going blood flow through the vessel 880 isfacilitated by the channel spaces defined between the ribs 756 of thestabilization balloon 754.

Referring to FIG. 9, another embodiment of a rotational atherectomy caninclude an alternative rotational atherectomy device 900 and thepreviously described flush tube 750, which can be used together toprovide an atherectomy treatment to a stenotic lesion 990 within atargeted vessel 980. In this embodiment, the rotational atherectomydevice 900 includes a distal stability element 930, but does not includea corresponding proximal stability element. Rather, the stabilizationballoon 754 of the flush tube 750 provides the function of stabilizingthe portion of the drive shaft 910 that is proximal of the abrasiveelement 940 during high-speed rotation of the drive shaft 910. Thus, thestabilization balloon 754 and the distal stability element can work intandem to provide a stable and predictable rotary motion profile inwhich the shaft portion that is proximal of the abrasive element 940(and immediately adjacent to the balloon 754) and the other shaftportion that is distal of the distal stability element 930 remaingenerally aligned with the axis of rotation 903, even though theparticular portion of the drive shaft 910 adjacent to the abrasiveelement 940 is not generally aligned with the axis of rotation 903 (andinstead orbits around the axis 903).

A number of embodiments of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention. Forexample, design features of the embodiments described herein can becombined with other design features of other embodiments describedherein. Accordingly, other embodiments are within the scope of thefollowing claims.

What is claimed is:
 1. A rotational atherectomy device for removingstenotic lesion material from a blood vessel of a patient, the devicecomprising: a rotary actuator: an elongate flexible drive shaftcomprising a torque-transmitting coil having a constant outer diameterand defining a longitudinal axis, the coil configured to transmit atorque from the rotary actuator, the drive shaft being configured torotate about the longitudinal axis; multiple spherical abrasive elementsthat are attached to the drive shaft such that a center of mass of eachabrasive element is offset from the longitudinal axis of the drive shaftand that each abrasive element is spaced apart from an adjacent one ofthe spherical abrasive elements by an element separation distance; adistal stability element that is fixed to the drive shaft and that has acenter of mass aligned with the longitudinal axis of the drive shaft,the distal stability element being distally spaced apart from adistal-most element of the spherical abrasive elements by a distalseparation distance, the distal separation distance being greater thanthe element separation distance; and a coating along the drive shaft andthe distal stability element such that the coating surrounds an outerdiameter of at least a portion of drive shaft.
 2. The device of claim 1,wherein the drive shaft has a central lumen extending along thelongitudinal axis that is configured to receive a guidewire.
 3. Thedevice of claim 1, wherein the coating surrounds the exterior surfacesof the distal stability element, and an abrasive outer surface of theabrasive element is uncoated and outwardly exposed.
 4. The device ofclaim 1, wherein the coating comprises a fluid-impermeable material thatprovides a fluid-impermeable lumen along the drive shaft.
 5. The deviceof claim 1, wherein the coating has a different durometer at differentlocations on the drive shaft.
 6. The device of claim 1, furthercomprising a proximal stability element and a second distal stabilityelement, wherein the proximal stability element is located proximally tothe abrasive element and the second distal stability element is locateddistally to the abrasive element.
 7. The device of claim 1, wherein themultiple abrasive elements comprise three abrasive elements positionedadjacent to one another along the drive shaft.
 8. The device of claim 1,wherein the multiple abrasive elements comprises at least three abrasiveelements, and wherein a middle abrasive element has a larger outerdiameter than a proximal abrasive element and a larger outer diameterthan a distal abrasive element.
 9. The device of claim 1, wherein thedistal stability element is spaced apart from the abrasive element by astability spacing distance.
 10. The device of claim 9, wherein the driveshaft comprises a distal-most extension portion that extends distally ofthe distal stability element for a distal extension distance.
 11. Thedevice of claim 10, wherein the distal extension distance issubstantially greater than the stability spacing distance.
 12. Thedevice of claim 1, wherein the distal stability element comprises ahollow cylinder that surrounds the torque-transmitting coil of the driveshaft.
 13. The device of claim 12, wherein the hollow cylinder has anexterior cylindrical surface that is smoother and different from anabrasive exterior surface of the abrasive element.
 14. The device ofclaim 12, wherein the hollow cylinder has an axial length that isgreater than a maximum exterior diameter of the hollow cylinder.
 15. Arotational atherectomy device for removing stenotic lesion material froma blood vessel of a patient, the device comprising: a rotary actuator;an elongate flexible drive shaft comprising a torque-transmitting coilhaving a constant outer diameter and defining a longitudinal axis, thecoil configured to transmit a torque from the rotary actuator, the driveshaft being configured to rotate about the longitudinal axis; multipleabrasive elements attached to the drive shaft such that a center of massof the abrasive element is offset from the longitudinal axis of thedrive shaft, each abrasive element having a spherical shape; a distalstability element that is fixed to the drive shaft and that has a centerof mass aligned with the longitudinal axis of the drive shaft, thedistal stability element being distally spaced apart from a distal-mostabrasive element by a distal separation distance that is greater than alongitudinal spacing between adjacent spherical abrasive elements of themultiple abrasive elements.
 16. The device of claim 15, furthercomprising a coating that surrounds the distal stability element. 17.The device of claim 15, wherein the distal stability element is a hollowcylindrical member having an inner diameter that surrounds a portion ofan outer diameter of the drive shaft.
 18. The device of claim 15,wherein the multiple abrasive elements comprises at least three abrasiveelements positioned adjacent to one another along the drive shaft. 19.The device of claim 15, wherein the multiple abrasive elements comprisesat least three abrasive elements segments, and wherein a middle abrasiveelement segment has a larger outer diameter than a proximal abrasiveelement segment and a larger outer diameter than a distal abrasiveelement segment.